France's main right-wing opposition party was close to collapse on Sunday after talks failed to resolve a bitter leadership dispute and an ex-prime minister vowed to take the battle to the courts.
The contested leadership vote has thrown into turmoil ex-president Nicolas Sarkozy's UMP - still reeling from its loss of the presidency and parliament this year - and raised the spectre of an unprecedented split on the right.
Called in to mediate the damaging dispute, party heavyweight Alain Juppe threw in the towel after only 45 minutes of talks between ex-prime minister Francois Fillon and party secretary general Jean-Francois Cope late Sunday.
Fillon quickly blamed his rival and raised the stakes by promising to turn to the courts.
"Jean-Francois Cope holds sole responsibility for a failure that hurts our party and, furthermore, undermines the image of political activity," Fillon said in a statement.
"Anxious to break the deadlock into which Jean-Francois Cope's successive power grabs have plunged our party, I will refer the matters to the courts to restore the truth of the results and give a voice back to (party) activists," he said.
Cope held his ground, saying he was awaiting the decision of a party electoral appeals commission. He did not want to "mix the judicial process with the political process," he added.
Fillon, 58, and Cope, 48, have traded accusations of fraud and bad faith since last Sunday's party vote ended with Cope ahead by a handful of votes.
Cope was declared the winner of the leadership battle by a margin of just 98 votes in a contest in which more than 150,000 party members voted.
The party electoral commission has since said that ballots cast in France's overseas territories that were not counted would have reversed the result. The Cope camp meanwhile has claimed he would have won by a clear margin but for vote-rigging in the Mediterranean city of Nice.
The party has faced ridicule over the debacle, at a time it could be taking advantage of Socialist President Francois Hollande's falling popularity over his handling of France's struggling economy.
And Sarkozy himself waded into the debate Sunday. He is attending a conference in Shanghai, but a source close to the ex-president told AFP he had telephoned Juppe and was "in favour of all initiatives that could resolve the situation".
But Juppe, a former prime minister and Sarkozy-era foreign minister, had expressed pessimism he could resolve the conflict. On Sunday evening, after the talks broke up, he said he was giving up his efforts.
"Alain Juppe, noting that his proposals were not accepted, considers that the conditions for a mediation did not come together," said a statement. "Therefore he considers that his mission his over."
The party's former secretary general, ex-labour minister Xavier Bertrand, urged the UMP to clean up its act and warned its existence was at stake.
"This spectacle, this image we have put forward this week, is shameful, not worthy of a great political party," he told France 2 television.
"We must emerge from the crisis we are sinking into, I don't think that in the last 10 years the UMP has ever been in as much danger."
In a IFOP poll published on Sunday in Le Journal du Dimanche newspaper, 71 per cent of respondents and 67 per cent of UMP supporters said the leadership vote should be run again.